THE USE OF MALDI-TOF MASS SPECTROMETRY WHOLE CELL PROTEIN/PEPTIDE PROFILES FOR IDENTIFICATION AND CHARACTERIZATION OF NOVEL STRAINS WITH PROBIOTIC PROPERTIES
| Authors | |
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| Year of publication | 2009 |
| Type | Conference abstract |
| MU Faculty or unit | |
| Citation | |
| Description | Introduction: In dairy industry, especially in case of the use of novel probiotic strains, there is a great need for relevant milk culture selection, its proper identification and characterization. In microbiology, modern methods in chemotaxonomy include widely used Matrix Assisted Laser Desorption/Ionization - Time of Flight Mass Spectrometry (MALDI MS). This fast, procedurally simple and sensitive analytical technique provides unique and highly reproducible fingerprints of bacteria (protein/peptide profiles). Profiles of proteins originating from cytoplasmatic membrane and cytoplasm are highly characteristic with great discriminatory power accessible by the analysis of intact bacterial cells. MALDI MS profiles can be effectively used for direct identification of microorganisms and for monitoring of their characteristics (culture changes, metabolic products etc.). Identification of bacteria samples is based on comparison of sample profiles with a database of the profiles of type and reference cultures. Besides bacteria identification MALDI-MS proved to be an efficient tool for taxonomic characterization and classification of unknown bacteria. Methods: After cultivation cells proteins/peptides were extracted according to standard procedure (Bruker) the final extracts were applied to MALDI target with appropriate matrix (alpha-cyano-4-hydroxy-cinnamic acid) and analyzed by MALDI-MS. MS data were processed with cluster analysis using BioTyper software (Bruker). Protein/peptide profiles could be influenced by the use of different cultivation media or by the growth phase of the cell. These aspects and optimization of MALDI-MS analysis were tested on CCM Bifidobacterium, Lactobacillus and Lactococcus type cultures. The overall aim of our study was to assess capabilities of MALDI MS profiling for reliable characterization of lactic acid bacteria. Results: Optimization process showed no influence of cultivation medium, prolonged cultivation and frozen sample storage on the resulting MALDI-MS profile and classification of samples. We obtained clear and rapid differentiation of 100 CCM and CCDM lactic acid bacteria strains. Cluster analysis of strains showed the capability of MALDI-MS to differentiate and to classify strains at the species/sub-species level. Discussion: The main advantage of MALDI MS approach is its rapidity (after cultivation of a pure strain the subsequent analysis is completed in 10 min) and the possibility of bacteria identification on the genus, species and strain level. |
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